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More than 2 devices in Active-Active mode?

Hi All, Can I have 4 LTMs in a cluster? 2 LTMs in one DC and 2 in another. Looking for active/active load balancing in 2 DCs. Looking for options. I can see documentation on 2 devices in Cluster.

Any one implemented F5 for active/active between DCs?

Appreciate your inputs, Thanks, Vidhya

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USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER

As for v11.4 capabilities here are the release notes that talk to that feature

http://support.f5.com/kb/en-us/products/big-ip_ltm/releasenotes/product/relnote-ltm-11-4-0.html#rn_new

"Connection mirroring for device groups: Prior to this release, you could only implement connection mirroring between a static pair of BIG-IP devices. Now, connection mirroring is based on traffic groups, so that an active traffic group can mirror its connections to its standby peer on the next-active device, regardless of which device in the device group is the next-active device"

Take a look at the user guide at

http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-device-service-clustering-11-4-0/9.html

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Comment made 26-Mar-2014 by Vidhya 81
Thanks much!
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USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER

I have 6 in one of mine... But that's a production one with standby sites using HAGroups

I have a 4 node cluster with 2x floating traffic groups...

And another 4 node cluster with 1x floating traffic group and 2 of the nodes with non-floating traffic groups hosting APM...

Lots of options. v11 is very flexible. 11.4 is the one you really want though because you can set proper priorities on the traffic groups to decide which order they move between cluster nodes.

H

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Comment made 24-Mar-2014 by Vidhya 81
Thanks Hamish! Appreciate your help! I havent seen much documentation on the active active of more than 2 nodes. Would you have any to point it out for me? Thanks! Vidhya
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Comment made 26-Mar-2014 by Vidhya 81
Got one for the 11.5 link, incase someone has a similar query and looking for a quick link. http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-device-service-clustering-admin-11-5-0.html
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USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER

Active active is a total pain in the butt to manage and I would avoid it at all costs. It sounds great on paper and to executives, but the daily operation of it would add allot of work to your day.

It would be up to you to manually balance out the load for every virtual address by putting them in different traffic groups. Also, depending on the number of devices you have and the normal load percentage on them, the number of traffic groups might have to be double or more the number of LTMs you have. This is because you may need to split the load from one failed LTM across multiple devices that are in standby for those traffic groups.

Let's say you have 3 devices running at 55% load each. If one LTM fails then another device will pick up the traffic group and that device will be running at 110%. So in that case you need 6 traffic groups so that a failure of one device would split the load of two traffic groups (27.5% each) across the remaining devices so that each would have 82.5%.

Not a whole lot of fun in my opinion.

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Comment made 23-Mar-2014 by Patrik Jonsson 3501
Well said. Even though there is some scenarios where it makes sense, I would never recommend active unless it's really needed, and even then with ample redundancy in terms of performance.
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Comment made 23-Mar-2014 by Hamish 3361
I never buy this argument about 'overloading' on failure of a cluster node. Good planning can alleviate that. As can keeping an eye on capacity. Plus running active/active generally means less downtime in the event of a failure, and fewer surprises when you discover that your standby system isn't quite as ready to take load as you thought... H
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Comment made 25-Mar-2014 by Eric Flores
"Good planning can alleviate that. " That is kind of the point I was making. All of that "planning" is the manual distribution of VIPs and traffic groups.
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USER ACCEPTED ANSWER & F5 ACCEPTED ANSWER

Vidhya,

You can have up to 8 devices in a sync-failover Device group. They can all be active for traffic groups and be standby for other traffic groups too.

You can have active/active between DCs, as long as the routing is sufficiently in place.

N

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Comments on this Answer
Comment made 21-Mar-2014 by Vidhya 81
Thanks so much! This is what I was looking for.
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